One of the many milestones your baby will take.

Many parents view crawling as such a significant milestone that they experience great excitement when it happens—and great worry if it seems to be delayed.

But a small percentage of children never crawl at all and move right on to walking, and this is perfectly normal, according to Marilyn Bull, M.D., F.A.A.P., a professor of pediatrics at Riley Hospital for Children in Indianapolis.

Research shows that skipping crawling has no effect on a child's development; but if your baby hasn't begun moving by 11 months and you're concerned, talk to your pediatrician.

For babies who do crawl, the big event usually happens anywhere between 4 months and 12 months of age. Once they start to move, some develop unconventional styles of locomotion, such as scooting on their bottoms; these are nothing to worry about. What you should worry about is keeping your baby in a car seat unnecessarily. "Car seats are the very worst thing for motor skill development," says Bull. "They don't allow a child any movement, not even their head."

So while safety seats are an absolute must for car travel, use them only when in the car. "Keep a mat or large towel with you so you can place your baby on the ground nearby in case you need to, for instance, watch an older child play soccer," Bull suggests. While you're at it, give your baby plenty of tummy time from Day One; crawling requires gross-motor skills, as well as neck and back strength, which belly time helps develop.